Dual-voltage explosionproof motor



Dec. 17, 1935. EHRENFELD 2,024,726

DUAL VOLTAGE EXPLOSIONPROOF MOTOR Filed Dec. 12, 1953 5 Sheets- Sheet 1 WHTNESSES: INVENTOR 1 a fi as/fh hren/e/a. K/ W Dec. 17, 1935. R. EHRENFELD 6 DUAL VOLTAGE EXPLOSIONPROOF MOTOR Filed Dec. 12, 1935 a Shee ts-Sheet 2 WITNESSES: INVENTOR Dec. 17, 1935.

R. EHRENFELD 2,024,726

DUAL VOLTAGE EXPLOSIONPROOF MOTOR Filed Dec. 12, 1953 5 Sheets-Sheet 3 #7 vI 1 M5 /05 37 WITNESSES:

INVENTOR Patented Dec. 17, 1935 UNITED STATES PATENT OFFICE DUAL-VOLTAGE EXPLOSIONPROOF MOTOR Ralph liihrenfeld, Springfield, Mass, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of My invention relates to electric motors and particularly to explosion-proof dual-voltage motors.

An object of my invention is to provide an explosion-proof motor assembly containing within a motor housing a circuit controlling switch and a connection-changing switch for the motor field winding.

Another object of my invention is to provide a relatively simple and efiicient change-over switch mounted in an explosion-proof manner within a motor housing to permit the motor to be operated on either one of two different line voltages.

Another object of my invention is to provide a change-over switch the contact members of which are located inside of a motor housing while the actuating and indicating part thereof is located outside of the motor housing and has two limiting operative positions in each of which it can be positively located and held.

Other objects of my invention will either, be apparent from the following description or will be pointed out hereinafter.

In practicing my invention I provide a totally enclosed motor, the housing of which is so designed and constructed as to be explosion-proof,

and located inside of this housing a switch con-' trolling the energizing circuit of the motor and also a field changeover switch, both of the switches being actuable from the outside of the motor housing.

In the drawings:

Figure l is a view in vertical longitudinal section through a motor assembly embodying my invention;

Fig. 2 is a view mainly in end elevation with a small portion broken away, of the structure shown in Fig. l;

as this motor is a dual-voltage motor, the energizing or stator winding is made in two sections, shown diagrammatically in Figs. 5 and 6, of the drawings, and there designated by the numerals I5a and l5b respectively. 5

A rotor structure is rotatably mounted inside of the stator casing II and comprises the usual set of rotor laminations l1, a rotor winding 19 and a commutator 2|, all amembled in a manner well known in the art, on a rotor shaft 23. The commutator 2| has associated therewith a plurality of brushes 25, only one of vwhich is shown in Fig. 1 of the drawings, it being understood that the proper number of brushes are provided, mounted in brush holders 21, one of which is shown in Fig. 1 of the drawings.

I have illustrated an alternating-current motor of the so-called repulsion-induction type and the rotor shaft 23 has mounted thereon a collar 29 upon which are mounted a plurality of centrifugally-actuable weight members 3|, each of substantially T-shape, the inner end portions of the members 3| being located in a recess in collar 29 and the outer ends of the weight members 3| being engaged by a garter spring 33. A device of this kind is well-known in the art and is operative to short circuit the commutator when the rotor has attained to almost its normal operating speed, the position of the commutator short-circuiting device being shown below 30 the axis of the shaft when the rotor is at rest, and being shown in the position occupied during normal running of the motor in the view above the axis of the shaft.

A pulley-end bearing bracket is provided 35 having a bearing therein, and a commutator endbearing bracket 31 is provided at the other end of the motor casing, these two bearing brackets being severally provided with radially extending Fi 3 is a f a m s t a vi w n a portions 39, as shown more particularly in Fig. 2

enlarged scale taken on the line III-III of of the drawings, to provide apertured ears Fig. 2; through which a plurality of clamping bolts 4| F 4 s a a m ntary sectional view on an may extend at one end through bearing bracket enlarged Scale taken on the line o g. 35, while having screw threaded engagement in 45 1; and

Figs. 5 and 6 are diagrams of connections of the motor circuit showing more particularly the change-over switch.

A motor casing H may be of substantially cylindrical shape and be made either of a casting or of a rolled-up metal plate, and a set I 3 of stator laminations is located inside of the casing and held therewithin in any desired manner. An energizing winding I5 is shown in Fig. 1 in its entirety, and it is to be understood that,

the other bearing bracket 31.

As is well known in explosion-proof motors, it is necessary not only that all of the housing parts of the motor be relatively strong, but also that any openings of any kind, such as joints between interfitting parts of the motor assembly, shall be so designed and constructed as to present a sufilciently long path between the inside and the outside of the motor, that any flame occurring in the motor will be entirely quenched before it reaches the outside of the motor. To this end the respective bearing brackets 35 and 31 are made relatively heavy and the central bosses thereon for receiving and supporting the respective bearing sleeves 43 and 45 are made relatively long. A dishedmember 41 is located in the opening in which the bearing sleeve 43 is located, and a somewhat similar dished member 453 is located outside of bearing sleeve 45. These dished members are efiective in retaining the oil provided for the bearings; and it is to be noted that while no particular means have been shown in the respective bearings for oiling the same, it is to be understood that any desired means effective for this purpose may be utilized and has not been shown as it constitutes no part of my present invention. v

The commutator end bearing bracket 31 is provided with a pair of recesses therein designated respectively by the numerals 5I and 53, both re- CE'ESQS being adapted to be closed by cover members, cover member 55 over recess 5I being adapted to be held in place by. a plurality of heavy machine screws 51, as shown in Fig. 2 of the drawings, while cover member 59 over recess 53 is adapted to be screwed into place.

Recess 53 is provided to permit of introducing into the motor structure a pair of conducting leads iI and 63 which are adapted to be connected to a suitable source of electric energy. The leads 6! and G3 are located in a conduit 65, screwed into the walls of an opening 61 and there extend through a bottom wall 69 surrounding the recess 53. The leads extend through a rear wall H back of recess 53 in a somewhat similar mannor, that is through a suitable flame-proof seal or gasket '53 which may be of such shape as to be held by reason of its configuration in an opening in wall II. The seal 13 is preferably made of litharge and glycerin which hardens to form a strong flame resisting mass.

The recess 5| is utilized for the support of a toggle switch I5 provided with an operating 'handle Tl shown more particularly in Fig. 1 of the drawings. The front wall of cover 55 is provided with a boss extending both in front of and in the rear of wall 55 in order to provide sufiicient depth to meet the requirements for an explosion-proof construction. These bosses have an opening i9 therein through which there extends a rod BI on the inner end of which is fixedly secured so as to turn therewith, an arm 83 at the outer end of which there is mounted a fork of resilient material (see Fig. 4), the two sides of the fork 85 being located, one at each side of toggle arm ii to actuate the same upon turning movement of shaft 8I. At the outer end of shaft SI there is located an arm 81 having one end secured against the outer end of shaft 8I while its other end may be provided with an opening 38 to receive some kind of an actuating rod. Motors of this general type thus far constructed have 'been for use in connection with gasoline pumps and are located in an enclosure necessitating some arrangement whereby an operator can effect turning movement, first in one direction and then in the opposite direction, of arm 8? and therefore of shaft 8! and of members 83 and 85 whereby to actuate toggle switch 15 to its open or to its closed position.

As has already been stated hereinbefore, one of the elements of my invention has to do with a change-over switch by which the .two parts of the stator winding can be connected, either in parallel for operation on a 110 volt circuit, or in series circuit relation relatively to each other, for

the actuation of the same from the outside of the 10 motor.

The change-over switch structure includes a fixed plate 9| of electric-insulating material which may be held against an inner face of bearing bracket 31 provided for that purpose by one 15 or more machine screws 93, only one of which is shown in Fig. 3 of the drawings. Against the outer face of member 9I are mounted four fixed contact members 95, 91, 99 and IN, respectively,

(see Figs. 5 and 6), which are connected as shown 20 in Figs. 5 and 6 of the drawings, to the respective terminals of winding sections I 5a and I51), and also to the supply circuit leads BI and 33, the circuit-controlling switch I5 being also connected in circuit in substantially the manner shown.

A movable disc I03 is fixedly mounted on the inner end of a short shaft I05 to turn therewith, and on the outer face of disc I03 there are mounted in any suitable manner two contact bridging members I 01 and I09. When the disc I03 occupies one of its limiting positions, as by the cooperation of one of the screws 93 fitting into a peripheral recess of predetermined arouate extent, contact bridging member I0! will be engaged by terminals 95 and 91 while bridging member I09 will be engaged by terminals 99 and I 0|, whereby the two sections I5a and I 5b are connected in parallel relation to each other and are therefore adapted for operation on the lower of two operating voltages.

In order to permit of turning movement of disc I03 and shaft I05, I provide a sector plate III rigidly secured'to the outer end of shaft I 05 in any suitable manner, which sector plate may be moved angularly in either one direction 5 or the other through an angle determined by the peripheral extent of the recess in disc I03 shown in Figs. 5 and 6 of the drawings;

As shown in Fig. 2 of the drawings, I may provide the disc I I I with two peripherally spaced openings therethrough, one of which is designated I I 3, the other being shown as filled by a machine screw H5. Only one opening II i (see Fig. 3) into the outer surface of bearing bracket 31 is provided, which is screw-threaded to re- 55 ceive the inner end of machine screw I I5. Thus, if an operator wishes to change the connections of thetwo winding portions I 5a and I 52) relatively to each other, he will unscrew and remove machine screw II5, move sector III until the second opening II3 registers with tapped hole II! and then replace machine screw H5. It is, therefore, obvious that accidental movement of the sector III and of the other parts connected therewith is substantially impossible and that 65 the operation of changeover from one position and connection to another requires a plurality of individual steps.

As shown in Figs. 5 and 6 of the drawings, the

sector I II may be provided with an arcuate slot 70 II 9, in which case it will not be necessary toremove machine screw H5 but merely to loosen it, after which the sector can be moved from one of its limiting positions to its other limiting position. The machine screw can be re-tight- 76 ened, and the parts controlled thereby will be held in the position to which they were moved. [is shown in Figs. 5 and 6 of the drawings, voltage values may be suitably stamped on the outside surface of disc Ill so that the operator may know by a visual inspection of the outside of the device for what voltage it is connected.

It is obvious that the provision of a stator winding in a motor of this kind comprising two portions which can be connected in series or in parallel with each other and the further provision of a relatively simple change-over switch actuable manually from the outside of the motor assembly makes possible the manufacture of a motor of this kind that can be operated selectively at either of two voltages, it being understood of course that a motor of this kind could be operated on either 220 or 440 volts as well as on either or 220 volts, by proper design, the values of 110 and 220 volts having been mentioned for illustrative purposes only.

The motor structure embodying my invention thus provides an explosion-proof motor assembly having a circuit-controlling switch located on the inside of the motor and actuable from the outside of the motor, as well as comprising a change-over switch to permit an operator to change the connections of the energizing winding sections to adapt the motor to operate on either one of two different supply-circuit voltages, the contact members of the change-over switch be g also located on the inside of the motor s.- cture and actuable from the outside thereof. it will therefore be noted that, by the help of the devices more particularly embodying my invention, I provide a motor which is substantially self-contained insofar as circuit-controlling devices are concerned, two conductors only extending outwardly of the motor to which the "usual supply-circuit conductors may be connected. It is obvious that this construction tends to a simplification in the structure and to the use of a minimum amount of space; particularly so, as the change-over switch requires no additional provision as to space and the ciredit-controlling switch requires only a relatively small additional space. Inasmuch as it is necessary to make the motor itself in an explosionproof manner, it is further obvious that if the necessary circuit-controlling devices can be located within the motor housing or structure, a much safer assembly will be obtained than would be the case where the circuit-controlling switches are located in explosion-proof casings auxiliary to the motor itself.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.

I claim as my invention:

1. A dual voltage motor assembly comprising a stator housing, a pair of bearing brackets thereon,

a stator, energizing windings thereon, a changeover switch for the energizing windings mounted 5 on the inside of one of the bearing brackets, means extending through the bracket for actuating the switch to one or the other of two operating positions, operating means disposed on the outside of the bracket and cooperating with the switch actu- 10 ating means, and locking means for the switch operating means on the outside of the bracket and cooperating therewith to limit the movement of the switch and define two limiting positions of the switch. 15

2. A dual voltage motor assembly comprising a stator housing, a pair of bearing brackets thereon,

a stator, energizing windings thereon, a changeover switch for the energizing windings mounted on the inside of one of the bearing brackets, 29 switch-actuating means including a rod extending through the bracket and a plate rigidly secured to the outer end of the rod and having two spaced openings therethrough, and a locking means for the plate extending therethrough and interfitting 2.3 with the bearing bracket.

3. A dual voltage motor assembly comprising a stator housing, a pair of bearing brackets thereon,

a stator, energizing windings thereon, a changeover switch for the energizing windings mounted 30 on the inside of one of the bearing brackets, switch-actuating means including a rod secured at its inner end to one part of the switch and extending through the bracket in an explosion-proof manner, a plate rigidly secured to the outer end of the rod closely adjacent to a part of the outer surface of the bracket and having two spaced openings therethrough, and a single screw adapted to extend selectively through one of said openings and into the bracket at only one point.

4. A dual voltage motor assembly comprising an imperforate stator housing, imperforate bearing brackets one at each end of the housing, a rotor and a stator assembly in the housing, supply circuit conductors extending into the motor as- 45 sembly through one of the brackets and sealed therein, a circuit-interrupting switch located within the assembly and supported by said one bracket, externally accessible means for actuating the circuit controlling switch, a change-over 5 switch supported by said one bracket on the inside thereof, means including a sector plate located adjacent the outside surface of the bracket for actuating the change-over switch from the outside of the bracket and a locking means for 5 the change-over switch including a bolt extending through the sector plate and interfitting with the bracket.

RALPH EHRENFELD. 

